JPS63308043A - Film and sheet for concrete curing - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a curing film and sheet for concrete, etc. when molding various types of concrete or mortar using formwork.

<Prior Art> In order to give the ready-mixed concrete or mortar, etc., a suitable fluidity so as to completely fill the corners of the formwork, surplus water in excess of the amount of water required for hardening is added. Therefore, when it is compacted with a vibrator etc., it tends to turn into pleating water and cause air bubbles to form, and when hard mixed concrete is used as ready-mixed concrete, a large amount of air bubbles are likely to be mixed into the concrete during pouring.

The formwork used for concrete work is usually composed of a weir plate and a template made of iron or wood, and the surface that comes into direct contact with the concrete is impermeable and air-permeable. It was a board. Therefore,
On the surface of concrete from which the formwork has been removed after curing, so-called pockmarks appear, which are traces of water bubbles that have accumulated on the side of the formwork and air bubbles that have entered the concrete.

The occurrence of these pockmarks not only impairs the beauty of the concrete surface, but also causes problems such as a decrease in the surface strength of the concrete and a decrease in durability.

In recent years, in order to solve these problems, water-permeable and breathable non-woven or woven fabrics made of polyolefin, polyester, nylon, etc., have been used by pasting them on the formwork.

<Problems to be Solved by the Present Invention> These conventional materials have the following drawbacks. In other words, these nonwoven or woven fabrics are effective in reducing pockmarks formed on the concrete surface due to blisters and air bubbles due to their breathability and water permeability; however, the surface of nonwoven or woven fabrics is Because it has an uneven surface, the surface of concrete after curing will be in a state where the uneven surface due to the fibers of the non-woven fabric or woven fabric is directly transferred, resulting in poor smoothness and not necessarily improved surface strength. is the current situation. In addition, due to the large voids in these non-woven fabrics or woven fabrics, it is easy for relatively fine-grained cement to penetrate and the fibers become buried in the cement. Currently, the surface of nonwoven or woven fabrics suffers considerable damage such as cracks and cannot be reused because the peeling properties are poor and the peeling resistance is high even when detached.

Therefore, there is a problem in that this results in an expensive curing method.

The present invention overcomes the problems when using these conventional materials, and the concrete surface after curing is beautiful and free of blemishes, so that concrete with high surface strength and excellent durability can be obtained. The present invention provides a concrete curing film and sheet that can be cured at low cost.

<Means for Solving the Problems> As a result of intensive research to develop a method for curing hydraulic compositions such as concrete or mortar with excellent strength and a surface, the inventors of the present invention have developed a method for curing hydraulic compositions such as concrete or mortar with excellent strength. The inventors have discovered that a method of using a porous polyolefin film layer or a laminate of the same and a reinforcing material as a concrete curing sheet is extremely effective, leading to the completion of the present invention.

That is, the present invention comprises a porous polyolefin film layer, has an air permeability of 10° to 1038 ec/100cc, and has a water permeability of 10' to 100 liters under a pressure of 0.2 kg/d.
/rrfhr, a concrete curing film comprising a porous polyolefin film layer and a reinforcing layer, and having an air permeability of 10° to 10'see/1.
00 cc and a water permeability of 10' to 1041/rdhr under a pressure of 0.2 kg/c1M.

In this invention, the term "film" is a general term for membranes, and the term "concrete curing" refers to the curing of concrete, mortar, or their pond hydraulic compositions.

The curing film and sheet of the present invention have an air permeability of 10° to 1
It is necessary to be in the range of 0'sec/100 cc, preferably 5 x 10° to 5 x 102see/10
It is in the range of 0cc. Air permeability is 10゜sec/100c
If it is less than c, the individual void size of the porous polyolefin film layer becomes large (as a result, relatively fine particles of cement enter the voids, which not only impairs the smoothness of the concrete surface after curing, but also causes the porous polyolefin film to This is undesirable because the releasability of concrete in the film layer deteriorates.If the air permeability exceeds 10"sec/100cc, deaeration becomes insufficient and pockmarks due to blisters and air bubbles occur, which is undesirable.

Also, the water permeability under 0-2kg/cJ pressure is 101~
100 1/rdhr, more preferably 3 x 10' to 3 x 10'' 1/rrrhr
within the range of If the water permeability under 0.2 kg/c-d pressure is less than 101/rrfhr, if the water content is high, blisters and air bubbles will be insufficiently removed and pockmarks will tend to occur on the concrete surface. Also 0.2kg/cd
When the water permeability under pressure exceeds 10"1/rdhr, more water than necessary is dehydrated before curing, and the strength of the concrete tends to decrease due to the formation of cavities and the like.

The curing film and sheet of the present invention can be manufactured by adjusting the above-mentioned air permeability and water permeability by changing the size, number, porosity, etc. of voids in the porous polyolefin film layer. Depending on the type of ready-mixed concrete, choose as appropriate, such as main concrete that contains excess water, relatively hard-mixed ready-mixed concrete, or ready-mixed concrete that requires almost no dewatering. Some non-woven fabrics and woven fabrics have the disadvantage that large uneven surfaces are formed on the surface of the curing concrete due to their uneven surfaces, but the porous polyolefin film layer of the present invention has excellent smoothness and air permeability. A significantly better surface of concrete can be obtained by using . This also significantly improves the workability of the curing film and sheet of the present invention. With conventional materials, the surface irregularities and pore sizes are large, so cement particles can enter the pores, causing damage to the surface of the curing film or sheet or causing concrete to adhere when the curing film or sheet is removed from the cured concrete. If a curing film or sheet made of porous polyolefin is used as in the present invention, the curing film or sheet has excellent releasability from cured concrete, and Hardly any concrete adhesion is observed during peeling, showing excellent workability.Of course, the cured concrete obtained is also highly smooth, so it is not only beautiful but also has excellent concrete surface strength and durability. Significantly improved. As described above, the curing film and sheet of the present invention have been recognized to have many excellent advantages not found in conventional curing methods, and bring remarkable effects to surface treatment of concrete using formwork methods. .

Constituent materials of the curing film and sheet of the present invention include:
A porous plastic film is required. Porous plastic films can be made by mechanically making the film porous using, for example, a needle, by removing the solvent from a plastic film that contains a solvent, or by adding a liquid such as a solvent to make the film porous. The so-called wet method involves pre-containing a filler that can be dissolved in plastic in the plastic, and then dissolving and removing the filler with a solvent after processing the film to make it porous.Furthermore, the plastic film or sheet containing the filler is stretched. There are methods to make the material porous. Among these, a dry method in which a filler-containing film is stretched is preferably used as a method that is easy to process and can be produced industrially at low cost.

The method for producing the concrete curing film of the present invention will be specifically explained below.

The polyolefin includes, for example, a monoolefin polymer such as ethylene, propylene, butene, etc. as a main component. For example, high density boethylene, medium and low density boethylene, crystalline polypropylene, crystalline ethylene-propylene block copolymer, polybutene, poly-3-methylbutene-1, polymethylpentene-1, ethylene-
There are vinyl acetate copolymers and mixtures thereof.

Further, as the filler, there are commonly used inorganic and organic fillers, such as the following. That is, examples of inorganic fillers include calcium carbonate, basic magnesium carbonate, sodium aluminosilicate, potassium aluminosilicate, lithium aluminosilicate, aluminum hydroxide, magnesium hydroxide, calcium oxide, magnesium oxide, silica, alumina, and titanium oxide. , clay, talc, bolastonite, barium sulfate, calcium sulfate, etc. are used as organic fillers.
Cellulose powders such as wood flour and bulb powder are used.

These may be simple or a mixture of two or more. In addition, regarding the average particle size of the filler used, when blending the above-mentioned filler with polyolefin, it is preferable to add various stabilizers such as heat stabilizers and light stabilizers. In order to improve film formability and stretching processability and stably achieve the desired stretching ratio, it is preferable to incorporate the following various additives. For example, higher fatty acids, fatty acid metals, etc. There are salts, cyanate esters, titanate esters, etc. As the higher fatty acids, saturated or unsaturated fatty acids having 4 or more carbon atoms are preferable, and those having 8 or more carbon atoms are particularly desirable.As the metal salts of fatty acids, Fatty acid salts having 8 or more carbon atoms are preferred, and those having 10 or more carbon atoms are particularly desirable. In addition, as a cyanate ester, RNCOLOCN (CI
□) There are isocyanates and diisocyanates represented by the general formula NCO. Furthermore, as the titanate ester, -i formula is Ti(OR')4. Ti(OR')
(OR)z, Ti(OR')t (OR)g. (Here, R and R'' are saturated or unsaturated linear or branched hydrocarbon groups.) The filler can be blended into the polyolefin using a -shaft or twin-screw extruder, a kneader, a Banbury mixer, etc. - There are methods using various kneading machines such as rolls and the like.

The blending amount of the filler is 20 to 80% by weight in the composition consisting of the filler, polyolefin, and additives, and the more preferable blending amount of the filler is 40 to 70% by weight from the viewpoint of air permeability and water permeability.
It is. If the concentration of the filler is too low, the air permeability and water permeability will be too low, making it impossible to completely degas the water bubbles that have accumulated on the formwork side and the air bubbles that have entered the concrete.

Furthermore, if the concentration of the filler is too high, the moldability of the film or sheet will deteriorate, which is undesirable.

As a method for producing a stretched polyolefin film containing a filler, there is a method in which a film is produced by a conventional film forming method such as a T-die method or an inflation method, and then the film is uniaxially stretched or biaxially stretched. Stretching ratio is 1.5~
Although it can be carried out within a range of 10 times, a stretching ratio of 3 to 8 times is usually preferred from the viewpoint of properties such as air permeability and water permeability.

If the stretching ratio is too low, the air permeability and water permeability will be too low, making it difficult to obtain the desired air permeability and water permeability. Stretching temperature is 30 to 140, which is too high, which is undesirable.
It is determined as appropriate depending on the melting point of the polyolefin used, the required stretching ratio, etc. within the range of °C. When the polyolefin is polyethylene, the temperature is usually 30 to 100°C, and when polypropylene is used, the temperature is preferably 70 to 140°C.

The thickness of the stretched film obtained by stretching is determined by taking into account air permeability, water permeability, strength, rigidity, etc., whether or not reinforcing material is laminated, and the type of reinforcing material to be laminated, but it is usually about 20 to 300 microns, preferably 40 microns. A thickness of ~200 microns is used.

The reason why a stretched polyolefin film containing a filler has air permeability and water permeability is because microvoids are formed in the film. These microvoids are produced by uniaxially or biaxially stretching polyolefin containing a filler as described above. The diameters of the microvoids are mostly distributed in the range from txto-'' to 5X10t microns, preferably the majority of the diameters of the voids are I x 1
It is preferable that the porosity is distributed in the range of 0-' to 2X10'' microns.The porosity is 20 to 70%, preferably 25 to 70%.
It is at 50%. The formation of such microvoids provides air permeability, water permeability, etc. suitable for concrete curing films and sheets.

In the present invention, the breathable porous polyolefin film can be used alone as a curing film, but laminating it with a reinforcing material takes into account the strength and rigidity level of the film used, which improves workability, strength, This is more preferable from the viewpoint of rigidity.

The reinforcing material used in the present invention is selected in consideration of the ability to be laminated onto the porous plastic film used and the strength, rigidity, air permeability, water permeability, etc. of the resulting laminate.

Examples include non-woven fabrics made of synthetic resin, tape yarn fabrics, nets, perforated sheets, and perforated plates, perforated sheets, and perforated tubes made of wood or metal.

Among these, tape yarn fabrics made of synthetic resin are preferred because they are lightweight and economically inexpensive.

Next, a specific manufacturing method will be described using a polyolefin tape as an example of a tape yarn fabric made of synthetic resin. The polyolefin tape can be made from the above-mentioned polyolefin, the above-mentioned filler-containing polyolefin, or a mixture containing these as main components and small amounts of other polymers, additives, etc. as raw materials.

The manufacturing method may be, for example, by slitting a film made by a method such as the T-die method or the inflation silane method to form a tape, and then weaving this tape.

Stretching either before or after forming the slits increases the strength of the tape, that is, the strength of the fabric, so it is preferable. When stretching, the stretching ratio is about 2 to 10 times, preferably 3 to 8 times. The fineness of the tape is preferably in the range of 200 to 2,000 deniers, particularly preferably in the range of 400 to 1,200 deniers.

The number of tapes per inch is preferably 2 to 20 per inch, preferably 4 to 15.
It is preferable to have a gap of 0.2 to 5 between the tapes in order not to impair air permeability and water permeability.The fabric composition of the tape yarn fabric is plain weave, diagonal weave, tie weave, layered weave,
Various conventional weaving methods such as pile weaving can be used. Among them, plain weave is preferred. A plain weave structure is preferable because it has a small surface unevenness, so it is easy to form a laminate with the stretched film.

Another preferable woven fabric is one in which the warp and weft are made of different materials to provide anisotropy in rigidity and flexibility, and such a woven fabric has the effect of improving the workability of concrete curing sheets.

Examples of a method for producing a laminate of a stretched filler-containing polyolefin film and a polyolefin tape fabric include a method of adhering or adhering the film and the fabric using a pressure-sensitive adhesive, an adhesive, or the like. The pressure-sensitive adhesive or adhesive can be applied either over the entire surface or partially in dots or strips. When applying the adhesive over the entire surface, care must be taken to ensure that necessary properties such as air permeability and water permeability are not impaired. hand,
Care must be taken to apply it thinly. However, a more preferable method is a partial adhesion method in which the adhesion points are uniformly distributed, and this method makes it easy to freely control important properties such as air permeability and water permeability. It is necessary that the adhesive strength between the film and the fabric be such that it does not easily peel off at least during construction and when the curing sheet is removed after concrete curing.

The adhesive to be used is preferably one with good adhesive strength such as a hot melt adhesive, urethane adhesive, or incyanate adhesive, and the adhesive is preferably a rubber adhesive.

There are various lamination methods, such as laminating the film on one side of the fabric, or laminating the fabric between multiple sheets of the fabric.Usually, the film is laminated on one side of the fabric. The form of laminating films is simple,
Cost is also low.

As mentioned above, polyolefin porous film and reinforcing material,
Furthermore, the specific manufacturing method of these lamination methods has been described, but this is just an example, and if it is a porous polyolefin film layer that has air permeability and water permeability suitable for a concrete curing sheet, the type of polyolefin and the porosity. The method, type of reinforcing material, and manufacturing method are not limited.

The present invention will be described in detail below, but the present invention is not limited to the scope of the examples. In addition, each characteristic in an Example was measured by the following method.

(2) Air permeability; Measured at 10 points using a Gurley densometer manufactured by Toyo Seiki Co., Ltd. (based on JIS-P8117), and the average value was determined.

(2) Amount of water permeation: The amount of water permeation was measured under a pressure of 0.2 kg/c-d using a membrane holder with a tank manufactured by Toyo Atvanchik Co., Ltd.

0 Surface smoothness: A photograph of the concrete surface after curing was taken. In addition, the presence or absence of rough skin on the surface was observed and evaluated by ranking.

○: Almost no surface roughness ×: Pockets or significant unevenness observed on the surface ■ Reworkability Adhesive weight: Weight increase of 8 after 5 cycles of use of the sheet peeled from the concrete after curing was measured, and the 8 weight increase is the sheet caused by concrete adhering to the

■Surface rebound hardness: The rebound hardness of the concrete surface after curing was measured using a Schmidt hammer.

■ Freeze-thaw test: concrete after curing at 5”C~-
The dynamic elastic modulus after 300 cycles at 18°C/3hr is J
It was measured according to IS-^1127, and the rate of decrease from the initial value was determined.

Example 1 Melt index (load 2.161cg, temperature 190
℃) (hereinafter simply referred to as Ml) 0.8 P/10 min, 50 parts by weight of high-density polyethylene with a density of 0.953 t/c-, and 50 parts by weight of heavy calcium carbonate powder with an average particle size of 15 μm were made into a ribbon. A mixture was prepared by mixing in a blender for 30 minutes.

To this mixture, 0.1% by weight of 2.6-ditert-butyl-4-methylphenol and 2.0% by weight of calcium stearate were added to produce a mixture of the four components, and the mixture was passed through a Banbury mixer. The mixture was heated and kneaded at 230° C. for 3 minutes to obtain a filled composition. Next, the mixture was formed into a sheet using a roll, and then granulated using a sheet pelletizer to obtain a pelletized filling composition. This filled composition was molded using an inflation molding machine "manufactured by Braco Co., Ltd., 50 φ extruder, die 150 φ" at a temperature of 180°C, a discharge amount of 35kg10r, a film thickness of 150μ, and a blow ratio of 2.
A film was molded under conditions of 0. Further, this film was stretched by a uniaxial roll stretching machine at a stretching temperature of 60''C1 and a stretching ratio of 5.
．． A stretched film was obtained at 0.0 and its physical properties were measured.

Next, a wooden cylindrical container (inner diameter 10
0φ, height 100 nn), then concrete (strength 300 kg/c- after curing for 28 days in 20°C water) was injected at a pressure of 0.6 kg/cd, and after curing for 24 hours. Concrete was obtained by dividing the cylindrical container, and the physical properties and reworkability of the concrete were evaluated.

Example 2 In Example 1, the thickness of the film obtained by inflating molding was 70μ, and the stretched film was coated with a urethane adhesive on a polyethylene tape yarn cloth of 900 denier 9 x 9 pieces/inch. Example 1 was carried out in the same manner as in Example 1, except that the sheets laminated together were used.

Example 3 Example 2 was carried out in the same manner as in Example 2 except that a polyester spunpond 40 r/rrr nonwoven fabric was used instead of the polyethylene tape yarn cloth.

Example 4 In Example 1, MIo, 8r/10 min, density 0.9
Example 1 except that linear low density polyethylene of 24 tr/ctl was used and the stretching ratio was 4.0 times.
It was carried out in the same manner.

Comparative Example 1 Concrete was poured into a metal non-porous container to obtain cured concrete.

Comparative Example 2 In Example 1, nylon 6 was used instead of the stretched film.
The test was carried out in the same manner as in Example 1, except that a 6-woven fabric (tensile strength: 500 y/3 cm width) was used.

Comparative Example 3 Example 2 was carried out in the same manner as in Example 2, except that an unstretched film obtained by inflation molding and having a film thickness of 70 μm was used instead of the stretched film.

Comparative Example 4 Example 1 was carried out in the same manner as in Example 1 except that the polyethylene tape yarn cloth used in Example 2 was used instead of the stretched film.

Table 1 shows the measurement results of Examples 1 to 4 and Comparative Examples 1 to 4. Further, surface photographs of the concrete obtained in Example 1.2 and Comparative Example 1.2 are shown in Drawings 1 to 4, respectively.

<Effects of the Invention> The present invention has excellent performance in air permeability and water permeability as a concrete curing film and sheet, and the concrete surface after curing using the same is beautiful and free from blemishes. To provide a concrete curing sheet that has high surface strength, excellent durability, can be manufactured at low cost, can be reworked, and is economically superior.

[Brief explanation of the drawing]

Figures 1.2 and 3.4 are enlarged photographs showing the particle structure of the surface of the concrete materials made in Example 1.2 and Comparative Example 1.2, respectively. No. 1 [1s2 m f3 5IJ14 Illustration procedure amendment July 21, 1988

Claims (4)

[Claims] (1) It is made of a porous polyolefin film layer and has an air permeability of 10^0 to 10^3 sec/100cc and 0.2
Water permeability under kg/cm^2 pressure is 10^1 to 10^4
A concrete curing film characterized by being l/m^2hr. (2) Composed of a porous polyolefin film layer and a reinforcing layer, with air permeability of 10^0 to 10^3sec/100cc
And the water permeability under 0.2kg/cm^2 pressure is 10
A concrete curing sheet characterized by being ^1 to 10^4l/m^2hr. (3) The porous polyolefin film layer contains filler 20
The concrete curing film according to claim 1, which is a stretched film layer made from a polyolefin composition containing ~80% by weight. (4) The porous polyolefin film layer contains filler 20
Claim 2, characterized in that it is a stretched film made from a polyolefin composition containing ~80% by weight, and the reinforcing layer is a polyolefin flat yarn woven fabric.
Concrete curing sheet as described in section.